Protective closure assembly for the Rocketdyne J-2 rocket engine's oxidizer valve, measuring 8″ in diameter and 2″ tall, marked on the top with the Rocketdyne logo and part no. "RX-20934-11NC." Contained in its plastic packaging with cleaning tag dated November 21, 1967. Accompanied by the original parts list and diagram showing the location of the closure on the J-2 engine; its purpose was to provide better protection for the valve and reduce the possibility of foreign objects entering it during handling and use. The J-2 was a liquid-fuel cryogenic rocket engine used on NASA's Saturn IB and Saturn V launch vehicles.
